Comparative analysis of SizerHX, RELAP5, and STAR-CCM+ simulations for microchannel heat exchangers. A case study using the E-SMR database

The application of compact heat exchangers in light water small modular reactors offers a promising area for improving nuclear technology thanks to high thermal efficiency and compact designs, making them suitable for integral designs. However, there is a notable gap in understanding their performance under liquid-boiling conditions, and a comprehensive database is currently lacking. This underscores the urgent need for further scientific research to address this gap. This study presents a preliminary design and analysis of a micro-channel heat exchanger, based on the E-SMR database developed within the ELSMOR project. The Python code SizerHX is presented and evaluated for its effectiveness in sizing compact heat exchangers. In the absence of experimental data, the code performance is compared to other simulation tools: RELAP5, a system code to evaluate the accuracy of heat transfer and pressure drop correlations, and to explore differences between the two-fluid and homogeneous mixture models; and STAR-CCM+, a computational fluid dynamics code employed to investigate potential three-dimensional effects that may not be captured by one-dimensional models. The preliminary analysis demonstrates good agreement between the models, with SizerHX proving to be a reliable tool. However, additional case studies are necessary to thoroughly evaluate the capabilities of SizerHX and experimental data will play a key role in validating and refining the model’s predictions. This data will be obtained from a dedicated facility currently under construction at Politecnico di Milano, specifically designed for testing compact heat exchangers.